Imaging properties of various gases in the environmental SEM

摘要

Interactions of high energy (primary and backscattered) and low energy (secondary) electrons with gas molecules are considered with regard to the imaging processes in low vacuum and environmental scanning electron microscopes. Effects discussed include scattering of the primary beam into a focussed probe surrounded by a skirt, cascade amplification of secondary electrons signals as well as background, and effects of ions impacting on specimen surfaces. Guidelines are given for predicting the behaviour of gases when designing experiments.